There is only one file type that uses the .XIP extension:
macOS Signed Archive
An XIP file is a .XAR archive that contains one or more files compressed or "zipped" using GNU Zip (gzip) compression that have been digitally signed. It also includes metadata such as certificates and the date and time the archive was created and modified.
XIP files are similar to .ZIP and .GZIP files but are digitally signed in order to verify that the contents have not been modified since the creator saved the file. This helps secure the file from any unwanted tampering and disk errors.
The XIP file is commonly used as a secure solution for delivering Xcode downloads. In the past, Xcode downloads have been tampered with in order to install malicious code into user's applications.
|Apple Archive Utility||Bundled|
Updated: March 7, 2017